Hollow-fiber bioreactor technology is an economical alternative to traditional cell culture methods for the production of cells and cell- derived products, and is finding increased use for novel applications in the fields of tissue engineering, gene therapy, and pharmacology. Hollow-fiber bioreactors are also reducing the suffering of animals by serving as logical replacements for ascites production methods. However, a major drawback of hollow-fiber technology is an inherent lack of predictability; there is no efficient screening method to determine how well a new cell line will perform in a hollow-fiber system, or how well an established cell line will perform under new conditions. To address this problem, a small, inexpensive, and easy to use screening tool has been developed at CELLEX BIOSCIENCES. This tool incorporates the same fibers as in a production system, but requires no pumping for oxygenation or medium delivery so that dozens of conditions can be tested simultaneously in a single incubator. This research will be used to test the validity of this micro hollow-fiber screening tool as a predictor of cell line performance in large scale hollow fiber systems. This tool has the potential of substantially increasing the efficiency and reliability of hollow-fiber systems, much as screening tools such as 96-well plates have done for stirred tank systems. PROPOSED COMMERCIAL APPLICATION Most importantly, a low cost screening tool will be developed and validated to fill a current market need. CELLEX could also use this tool along with other information learned in this research to provide a battery of screening tests as an optimization service. In addition, a new medium formulation specifically optimized for hollow-fiber bioreactors could be developed in this research.